DOI: 10.1615/TSFP8
CHARACTERIZING VORTICAL STRUCTURES IN THE LOWER LOG REGION OF THE ATMOSPHERIC BOUNDARY LAYER USING LARGE-SCALE PARTICLE TRACKING VELOCIMETRY
RÉSUMÉ
A large-scale particle tracking velocimetry (LS-PTV) system has been developed as a means of quantifying coherent structures within the atmospheric boundary layer. The LS-PTV system resolves three-dimensional, Lagrangian tracks over a volume of approximately 16m3. Mean velocity and Reynolds stresses have been validated and compared with wind-mast measurements and boundary-layer similarity formulations. The probability distributions for streamwise, spanwise and vertical velocity-fluctuation components agree with Gaussian distributions of equal variance. In contrast, the probability distributions for acceleration and vorticity are exponential and symmetric about zero. Thus, extreme acceleration events and vorticity events would be underpredicted by a Gaussian distribution. Finally, examples of particle paths exhibiting a high degree of swirl are presented, which are speculated to be signatures of large vortical structures.